More specifically the invention relates to a brush-holder of the type comprising: an electrically insulating support structure having an opening for receiving the commutator, around which retaining and guiding cages are fixed, each cage having, translatably mounted therein, a respective positive or negative brush, one end of which is intended to bear during operation against the commutator; the support structure comprising a molded-plastic body incorporating a first and a second conducting element intended to be connected to the positive and negative terminals, respectively, of an external supply-voltage source and connected to the positive and negative brush or brushes, respectively, via a first and a second connection path, respectively, so as to allow the brushes to be coupled to said voltage source; a discontinuity being provided in one of said connection paths; a resiliently deformable and electrically conducting strip being connected mechanically and electrically across said discontinuity with a substantially permanent connection at one end and with a heat-meltable connection at the other end and with a resilient pre-load tending to break the connection at said other end. Such a connection provides a thermal safely device protecting the motor from an excessive temperature rise which may result in the motor catching on fire
A brush-holder of the abovementioned type forms the subject of U.S. Pat. No. 7,696,665 in the name of the present Applicant/Assignee.
An object of the present invention is to provide an improved brush holder of the aforementioned type.
While such a brush holder works well with a single speed motor, when used in a two speed motor the thermal safety device may not operate sufficiently quickly to avoid an excessive temperature rise when the motor is operating on low speed.